Little is known about the association between psychosis and treatment outcomes in methamphetamine (MA) users. Using data from 526 adults in the largest psychosocial clinical trial of MA users conducted to date, this study examined psychiatric, substance use, and functional outcomes of MA users with concomitant psychotic illness 3 years after treatment. The presence of a psychotic disorder was associated with increased health service utilization and higher levels of psychiatric symptomatology across multiple domains over time. MA users with co-occurring psychotic illness may therefore benefit from early psychosocial and/or pharmacologic interventions to address psychiatric symptoms.